With the discovery of new synthetic roofing materials, the trend of the roofing industry has been to fabricate roofs, particularly flat, membrane covered roofs, from lightweight, structural components. Such construction produces less expensive roofs, and since the components exhibit relatively high strength per unit of structure weight, the roofs are capable of supporting greater working loads, for example, snow loads, and therefore, have become very popular. Typically, such roofing structures consist of a supporting framework on which is disposed a layer of decking material, and a layer of insulation fastened on top thereof. A weatherproof roofing material, often a synthetic, elastomeric membrane, is then attached to the lamination, completing the roofing structure. Such structures not only protect the interior of the building from the elements, but are relatively inexpensive, light, strong and durable.
Various methods have been proposed for fastening the insulation layer to the decking material, but for a variety of reasons, these have largely been unsatisfactory. It has been found, for instance, that the fasteners commonly employed tend to loosen, allowing the laminate layers forming the roofing structure to separate, ultimately compromising the ability of the roof to protect the building from the elements.